Programmable logic controller



FIG. 1 is a top, left, front perspective view of a programmable logic controller showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a rear elevational view thereof. 

The ornamental design for a programmable logic controller, as shown. 